Mixed adsorption characteristics of magnetic calcium silicate for Pb(II), Cd(II), and Cr(III) in solution

Abstract Adsorption methods have been widely employed for heavy metal wastewater treatment, yet traditional adsorbents pose challenges in terms of recovery. Magnetic adsorbent materials have garnered attention due to their ease of recovery and reuse. However, studies on their simultaneous adsorption of multiple heavy metal ions are limited. In this study, a magnetic mesoporous calcium silicate adsorbent (Fe 3 O 4 @MCS) was synthesized via an improved solvothermal and chemical precipitation method and applied to treat simulated wastewater containing Pb, Cd, and Cr ions. The adsorption capability of Fe 3 O 4 @MCS was assessed in a series of batch studies under a range of circumstances, including adsorbent dosage, pH, temperature, oscillation intensity, contact time, and initial metal concentration. The results demonstrated that Fe 3 O 4 @MCS exhibited excellent adsorption capacities for Pb, Cd, and Cr. Enhancements in adsorbent dosage, pH, temperature, and oscillation intensity improved the adsorption performance. After five cycles, the removal percentages of Pb 2+ , Cd 2+ , and Cr 3+ decreased by 21.48%, 13.56%, and 23.54%, respectively. The adsorption mechanisms were found to include surface precipitation, surface complexation, physical adsorption, and ion exchange.